LM 6.5: Disorders of Hemostasis Flashcards
what is a hypercoagulable state?
a tendency to thrombus under circumstances that would not cause thrombosis in a normal individual
can be inherited or acquired
can effect the venous &/or arterial circulations
what are thrombogenic risk factors?
- damage to the blood vessel wall
- activation of platelets
- activation of blood coagulation
- inhibition of thrombolysis and status of blood
what are protective mechanisms?
protect against a hypercoagulable state
- intact endothelium
- normal levels of antithrombin
- normal protein C&S levels
- normal function of the fibrinolytic pathway
- clearance of activation products of the coagulation pathway by the liver
what is arterial thrombogenesis?
platelets play the major role
usually develop in a diseased vessel where the blood is exposed to the damaged endothelium and subendothelium
what is venous thrombogenesis?
forms in areas of slowed or disturbed blood flow
thrombophilias may play a role
may occur in a healthy vessel
platelets play a secondary role
environmental factors play a significant role
which diseases are inherited thrombophilias?
they are all hyper coagulable states
- antithrombin deficiency
- protein C&S deficiency
- activated protein C resistance
- prothrombin G20210A
- hyperhomocystinemia
- hypoplasminemia
what causes activated protein C resistance?
due to point mutation in the factor V gene, factor V Leiden
what is antithrombin deficiency?
AT is produced by the liver and it inactivates coagulation factors, thrombin, Xa, IXa, XIa, and XIIa
factors 2,7,9,10,11,12
type I: deficiency of the protein
type II: reduced function but normal quantity of AT
which coagulation factors does AT inactivate?
thrombin, Xa, IXa, XIa, and XIIa
what is the inheritance pattern of AT deficiency?
autosomal dominant
most patients are heterozygous (40-70% of normal AT levels)
what are protein C&S?
they are vitamin K dependent tproteins
produced by the liver
they inactivate factors V and VIII
how is protein C&S deficiency inherited?
autosmal dominant
what is protein C&S deficiency?
type I: deficiency of the quantity of the protein
type II: deficiency in the function of the protein
what is activated protein C resistance?
point mutation in factor V gene causes abnormal factor V protein
abnormal factor V doesn’t allow activated C protein to lock onto it and neutralize the effects of factor V
so the coagulation cascade just keeps going = increased clotting
what are disorders of fibrinolysis?
reduced plasmin formation
can cause venous or arterial thrombosis but it’s not common
hypoplasminogenemia is an uncommon cause of reduced fibrinolytic activity
